> For the complete documentation index, see [llms.txt](https://docs.agentalk.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.agentalk.io/ai-agents/agent-functions/use-built-in-functions.md).
# Use built-in functions
Agentalk includes three built-in functions you can add to any agent without external setup: **End Call**, **Update Contact**, and **Transfer Call**.
Each function runs based on a trigger condition you define in plain language.
### Before you start
You need the following before you begin:
* You have an agent created. See [**Create an agent**](/ai-agents/create-an-agent.md).
* For Transfer Call, you need a phone number connected to Agentalk and a destination number. See [**Add a phone number**](/phone-numbers/add-a-phone-number.md).
* For Update Contact, you need to know which contact field the agent will update. See [**Manage contacts**](/contacts/manage-contacts.md).
To configure functions:
1. Go to **AI Agents** in the left navigation.
2. Open the agent you want to configure.
3. Select the **Functions** tab.
### Add the End Call function
Add the End Call function so the agent can end conversations cleanly.
1. In the **End Call Function** section, click **+ Add**.
The function is added with no additional configuration.
{% hint style="info" %} **Save your configuration changes**
Save your changes after adding the function.
{% endhint %}
The agent ends the call when:
* The conversation is completed.
* The caller asks to end the call, for example "bye".
You can edit or remove this function at any time.
### Add an Update Contact function
Add an Update Contact function to capture information from the conversation.
1. In the **Update Contact Function** section, click **+ Add**.
2. Configure the function:
* **Function Name**: Generated automatically.
* **Description**: Define when the agent should capture the data. Example: When the caller provides their email address.
* **Fields to update**: Select one or more fields:
* First Name
* Last Name
* Email
* Phone
3. Click **Create Function**.
{% hint style="info" %} **Save your configuration changes**
Save your changes after adding the function.
{% endhint %}
The agent updates the selected fields when the condition is met.
{% hint style="warning" %} **Create custom fields before using them**
Custom fields must exist before the agent can write to them. Go to **Contacts** to create them before using this function.
{% endhint %}
You can add multiple Update Contact functions to capture different fields.
### Add a Transfer Call function
Add a Transfer Call function to hand off the call to a human agent or team.
1. In the **Transfer Functions** section, click **+ Add Transfer Function**.
2. Configure the function:
* **Function Name**: Enter a name, for example `call_forwarding`.
* **Description**: Define when the transfer should happen. Example: When the caller asks to speak with a human agent
3. In **Phone Number Settings**:
* **Source number (Handover From)**: Select the current Agentalk number.
* **Target number (Handover Target)**: Enter the destination number.
Understand source and target numbers
Source number is the number your agent uses to handle the call.
Target number is the number where the call will be transferred.
Make sure a phone number is configured
If no numbers are available, make sure you have configured a phone number in Agentalk before setting up the transfer.
4. Click **+** **Add**.
{% hint style="info" %} **Save your configuration changes**
Save your changes after adding the function.
{% endhint %}
When a transfer is triggered, the agent leaves the call and the caller continues with the destination number.
### Save and test your configuration
After adding or updating one or more functions, save your changes and verify that everything works correctly.
You can add multiple functions before saving.
* Click **Save draft** to keep changes without activating the agent.
* Click **Save** to apply the configuration.
* Click **Save and test agent** to run a test call.
* Click **Cancel** to discard changes.
### Next steps
Here are the recommended next steps after completing this guide:
* [**Connect external APIs as functions**](/ai-agents/agent-functions/connect-external-apis-as-functions.md): Add custom logic and retrieve external data during calls.
* [**Manage contacts**](/contacts/manage-contacts.md): Configure contact fields used by the Update Contact function.
---
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